The Effects of Equine Assisted Therapy on Plasma Cortisol and Oxytocin Concentrations and Heart Rate Variability in Horses and Measures of Symptoms of Post-Traumatic Stress Disorder in Veterans.
Authors: Malinowski Karyn, Yee Chi, Tevlin Jenni M, Birks Eric K, Durando Mary M, Pournajafi-Nazarloo Hossein, Cavaiola Alan A, McKeever Kenneth H
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Equine-Assisted Therapy Effects on Horses and Veterans with PTSD This 2018 pilot study examined whether therapeutic interactions between nine experienced geldings and veterans diagnosed with PTSD produced measurable changes in equine stress physiology alongside improvements in human mental health outcomes. Over five consecutive days, researchers collected blood samples to measure plasma cortisol and oxytocin whilst seven horses wore electrocardiogram monitors to assess heart rate variability; veterans completed validated PTSD symptom inventories before and after the intervention period. Whilst veterans showed significant reductions in most PTSD symptoms following the five one-hour sessions, the horses demonstrated no meaningful changes in cortisol or oxytocin concentrations and showed no alterations in heart rate variability—suggesting they experienced minimal acute stress during these interactions, though equally offering no evidence of enhanced well-being. Heart rate did decrease significantly on day two during actual therapy sessions, indicating some physiological response, yet systolic and diastolic blood pressures remained unchanged in the veterans. For equine professionals involved in therapeutic programmes, these findings suggest that well-trained horses do not incur detectable stress elevations during EAAT work with this population, addressing an important animal welfare consideration, though practitioners should be cautious about claims of mutual physiological benefit and instead focus on the documented therapeutic gains for the human participants.
Read the full abstract on PubMed
Practical Takeaways
- •Therapeutic riding horses used in EAAT programs showed no signs of increased physiological stress (cortisol, oxytocin, HRV) during five 1-hour sessions, suggesting the activity did not negatively impact horse welfare in this cohort
- •While horses demonstrated modest physiological responses (lower heart rate during interaction), the lack of cortisol elevation or increased oxytocin indicates horses were not experiencing measurable well-being improvements or stress from the therapy sessions
- •Practitioners implementing EAAT should note that while the therapy benefited veterans' PTSD symptoms, the horses' physiological responses were minimal, requiring consideration of other welfare indicators beyond these specific biomarkers
Key Findings
- •Heart rate was significantly lower on day 1 during veteran interaction (P=0.006) and significantly reduced on day 2 during EAAT sessions
- •Plasma cortisol and oxytocin concentrations showed no significant changes in horses across EAAT sessions (P=0.821 and P=0.861 respectively)
- •Heart rate variability variables showed no significant differences in horses despite EAAT participation
- •PTSD symptoms in veterans were significantly reduced after five EAAT sessions except for interpersonal sensitivity (P=0.08) and phobic anxiety (P=0.17)